Subghz, lorawan, Nb IOT, Internet of things

It's a long name , It is as long as the closure and control of the epidemic in Shanghai . But the content is not much ,

• NB-IOT Introduce
• SubGHz and LoRaWAN Introduce
• IoT Architecture introduction

Talking about NB-IOT,LoRaWAN Before , Let's first look at the definition of low-power wide area Internet of things （LPWAN）.

In smart home 、 Short distance communication technology is generally used in LAN communication scenarios such as industrial data acquisition , But for a wide range 、 Long distance connection requires long-distance communication technology .LPWAN Technology is the long-distance wireless communication technology that came into being to meet the needs of the Internet of things .

LPWAN（low power wide area network）, Low power wan , Designed for low bandwidth 、 low power consumption 、 Remote 、 A lot of connected Internet of things applications .LPWAN It can be divided into two categories ：

One is working on unauthorized spectrum LoRa、SigFox Technology ;

One is working in the authorized spectrum ,3GPP Supported by 2/3/4G Cellular technology , such as EC-GSM、LTE Cat-m、NB-IoT etc. .

Low power wide area Internet of things （LPWAN） As one of the most important technologies in the Internet of things industry , At a compound annual growth rate 90% The amazing growth rate of . according to Global Market Insights The relevant research report shows , To 2027 year LPWAN The market size will exceed 800 Billion dollars .

Authorized spectrum camp with NB-IoT Technology first ; In the unauthorized spectrum camp LoRa Technology follows suit .

NB-IOT

The above said NB-IoT Work in the authorized spectrum , be based on 3GPP Supported by 2/3/4G Cellular technology , NB-IOT No need to rebuild the network , It can be deployed directly . I experienced it last month NB-IoT Door magnetic technology . The following picture shows the photos taken by volunteers after delivering supplies to their homes （ Look at the lower left corner ）. Volunteers can open the door for one time after notification . Then the linked police station and the district prevention and control personnel will receive a notice . Ready to install, ready to use , As convenient as a mobile card .


NB-IOT The signal is connected to the cloud through the cellular network base station , Processed by the cloud and pushed to the linkage command center . therefore NB-IoT It is often directly connected to telecommunications , Move , Unicom's cloud service .

At the chip level , The physical layer adopts OFMDA, Uplink adoption SC-FMDA, And LTE Almost the same , But more than LTE Simplify a lot , This has many benefits for the research and development of chips and production . The most mainstream chip manufacturers in China should be friends .

Take a picture NB-IOT Of NB The place of ：

Massive access ： Under the same base station coverage ,NB－IoT Skill is the number of other wireless access skills 50 to 100 times , existing NB-IoT The network single cell base station can access 5 10000 terminal devices , Such a large connection can make the Internet of things really “ All things connected ”.

Low power consumption ：NB-IoT There are three different power saving modes ：PSM Pattern 、DRX Pattern 、eDRX Pattern , The equipment can choose the point saving mode according to its own needs , Achieve the purpose of minimum power consumption , It can prolong the service life of the battery , For many battery powered devices and situations ,NB－IoT The low power consumption characteristics of the can ensure the endurance time of the equipment , From a few months to a few years , Therefore, the inconvenience caused by frequent battery replacement is greatly reduced .

Super coverage ：NB－IoT The coverage capability is LTE Of 100 times .NB-IoT The network has super coverage and super penetration ability , This can not only meet the needs of large-scale coverage in sparsely populated areas , It is also applicable to underground applications requiring deep coverage .

The cost is low ：NB-IoT Support in existing LTE Transformation on the network , It greatly reduces the cost of network construction ,NB－IoT No need to rebuild the network , RF and antenna can also be reused basically . Again NB－IoT low power consumption 、 Low bandwidth and low rate characteristics , It also reduces the cost of chips and modules .

SubGHz, LoRa, LoRaWAN

SubGHz seeing the name of a thing one thinks of its function , lower than 1GHz.Sub-GHz It is an ideal choice for long-distance and low-power communication . Wireless propagation is inversely proportional to frequency , At low power consumption 、 Long distance communication or wall penetration capability ,sub-GHz RF has more advantages . For many applications ,433MHz Become 2.4GHz Global substitutes for （ But Japan does not allow it to be used in wireless applications ）. be based on 868MHz and 915MHz The design of can be used in American and European markets . There are many available bands that do not require authorization or require authorization , For system integrators , You can choose to optimize the performance in some specific areas , Or cooperate with public utility companies to design systems in a wide area . In this diversity , And 2.4GHz Compared with the frequency band ,sub-GHz Frequency spectrum interference is less . The frequency band with less interference can improve the overall performance of the network , Reduce the number of retransmissions in transmission .

LoRa As a wireless technology , be based on Sub-GHz The frequency band makes it easier to communicate over long distances with low power consumption , It can be powered by battery or other energy collection methods . Lower data rates also extend battery life and increase network capacity .LoRa The signal is also very penetrating to the building .LoRa These technical features are more suitable for low-cost large-scale deployment of the Internet of things . In the city , Generally, the wireless range is 1~2 km , Suburbs or open areas , The wireless distance will be longer .

LoRaWAN Is based on LoRa Of wireless technology MAC layer .

LoRaWAN It is an open network protocol , Available from LoRa Alliance Standardized and maintained secure two-way communication 、 Mobility and localization services .

Compare with NB-IOT With the help of cellular network ,LoRa In the unauthorized spectrum camp . therefore LoRa Want to access the Internet of things , We need “Gateway”. Here's the picture ：

Gateway Will come from LoRa The data of the network is forwarded to the backbone network , Into the cloud .

Since entering the cloud , that gateway The implementation of is closely related to the connected cloud . Into whose cloud , Just use someone's SDK（ Development Kit ）.

Alibaba is the domestic cloud , tencent , Baidu , HUAWEI, etc. .

Amazon is the main one in the world AWS, Microsoft Azure, as well as Google GCP.

IoT Gateway implementation

it's a long story , First look at a picture of Microsoft

In the following pages, I will learn how to implement an Internet of things gateway on raspberry pie .